Enrolled trilobites

scale in cms

Along with the many crinoids, corals, brachiopods, and bryozoans found in the other limestones in this outcrop, this group of limestone beds commonly contains trilobites of the species Phacops rana, which are "rolled up" (enrolled) head-to-tail. Only certain types of trilobites are found this way.

Why did they roll up? For one possibility, look at the "sowbug" or "pillbug" (Armadillidium) that you might find under a rotting log. These flexible arthropods can roll up into a tight ball to protect their soft underside. Although not closely related, these modern land arthropods have a similar body design to the ancient sea-dwelling trilobites. Perhaps rolled up to defend themselves from predators and strong storm agitation.

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